Phillip Burgess.
"Mini Thermal Receipt Printer".
Tutorial at Adafruit.
This tutorial shows how to directly connect the
"TTL RS232" data interface on this particular printer
to an Arduino.
Then it shows how to program the Arduino
using the
Adafruit-Thermal-Printer-Library
at Github
to get print text, on-the-fly composed barcodes, and (hard-wired, pre-composed) arbitrary bitmaps.